Hose clamps with plastically deformed ear-like tightening devices known in the trade as so-called “Oetiker” ears have proved immensely successful and have been used in clamps commercially sold in the hundreds of millions. The success of the “Oetiker” ear is attributable to the holding ability of a clamp provided with such a tightening device as well as to the automatic compensation for aging and/or fluctuations in pressure and/or temperature of the fluid carried by the hose with which the clamp is used. However, these extraordinarily favorable operating characteristics are attainable only if the “Oetiker” ear is plastically deformed a sufficient amount by contraction of the ear so as to change the more or less rectangular hat-shaped configuration of the original “Oetiker” ear into an approximately omega-shaped configuration with a smoothly rounded external shape causing the corners of the hat-shaped configuration to disappear completely.
To achieve the desired plastic deformation of the “oetiker” ear, it is therefore necessary that the same be contracted a sufficient amount. U.S. Pat. No. 2,614,304 to Oetiker illustrates the desired plastic deformation in FIGS. 2 and 3 thereof. However, it is quite apparent that this necessary contraction of the “Oetiker” ear to achieve the desired plastic deformation is possibly only if the size of the clamp is such that there is sufficient play between the maximum diametric dimension of the clamp in the non-tightened condition and the external hose dimension, illustrated also in FIG. 2 of the '304 Patent. On the other hand, if maximum the size of the clamp in the non-tightened condition is such that it just barely fits over the hose, adequate contraction of the “Oetiker” ear seeking to reduce its diametric dimension is no longer possible. It may then happen that insufficient plastic deformation of the “Oetiker” ear will cause inadequate holding of the clamp.
My prior U.S. application Ser. No. 10/392,952, the subject matter of which is incorporated herein in its entirety by reference, already addressed this problem and suggested a lost-motion connection between overlapping band portions to permit plastic deformation of the “Oetiker” ear sufficient to achieve the desired plastic deformation without reduction of the diametric dimension of the clamp during contraction of the ear.
The maximum outer diametric dimension of a hose with which a clamp can be used has been normally determined by the mechanical connection between overlapping band portions. However, as the mechanical connection of a clamp according to my aforementioned prior U.S. patent application included a lost-motion arrangement, it no longer could function as the means for determining the maximum diametric dimension of the hose with which the clamp could be used and thus required a shift of this function to some guide members that had to be added and located in the clamp with sufficient accuracy to achieve the intended function. In contrast to the solution of my aforementioned prior U.S. patent application, the present invention solves the problem without such additional guide members, concentrating the solution to all problems in a mechanical connection according to this invention that can be readily incorporated into existing mass production techniques for such clamps by merely changing the design of the cutting dies.
In the case of so-called open-type hose clamps which utilized so-called guide hook members as disclosed, for example, in U.S. Pat. No. 3,321,811 to Thomas, there always existed the danger of reopening of the connection during the installation. The hook members as disclosed in the Thomas patent were thereby bent out of the band material through an angle α less than 90° which was intended to prevent normally reopening of the connection. However, as these hook members offered relatively little resistance to a further bending back by the circumferential forces that were exerted on the same during tightening of the clamp, connections with these hook members posed the inherent danger of reopening, for example, when these hook members were bent back through an angle of 90° or more. Any lost-motion connections utilizing such a hook member would thus be prone to the same problem.
As is well known in the art, clamps come in different sizes intended to cover predetermined ranges of diametric dimensions of the hose. The use of an improper clamp size on the assembly line which would preclude sufficient plastic deformation, is unlikely because the clamp sizes are normally carefully chosen for mass production. Additionally the installer would be made aware of the improper size by the likely destruction of the “Oetiker” ear with the use of pneumatically operated tightening tools that would destroy the “Oetiker” ear if it cannot be contracted because of the undersize of the clamp for a given hose.
The present invention also solves this problem by extremely simple means that prevent the installation of the clamp over a hose size that is too large in its diametric dimension for proper plastic deformation of the “Oetiker” ear.
Accordingly, it is an object of the present invention to provide a hose clamp which avoids the aforementioned problems by simple and reliable means.
Another object of the present invention resides in an open-type hose clamp which precludes the installation of an undersized clamp over an excessively large-sized hose.
Still a further object of the present invention resides in a hose clamp with a mechanical connection including a so-called guide hook member which assures proper lock-up of the mechanical connection during the entire tightening operation.